Steel is an alloy primarily made of iron and carbon, with various other elements added to achieve specific properties. The types of steel are categorized based on their chemical composition, production method, and application. Here’s a breakdown:
- Based on Carbon Content:
Low Carbon Steel (Mild Steel):
Carbon content: <0.3%
Properties: Soft, ductile, easily weldable, less brittle.
Uses: Automotive panels, pipes, structural applications.
Medium Carbon Steel:
Carbon content: 0.3–0.6%
Properties: Higher strength and hardness, less ductile than mild steel.
Uses: Railway tracks, machinery parts, shafts.
High Carbon Steel:
Carbon content: >0.6%
Properties: Very hard and strong, less ductile, difficult to weld.
Uses: Tools, springs, high-strength wires.
- Based on Alloying Elements:
Stainless Steel:
Contains chromium (10.5% or more) for corrosion resistance.
Subtypes:
Austenitic: High chromium and nickel (non-magnetic, corrosion-resistant).
Example: Kitchenware, medical equipment.
Ferritic: High chromium, low carbon (magnetic, less corrosion-resistant).
Example: Automotive parts.
Martensitic: Moderate chromium and carbon (magnetic, hard).
Example: Cutlery, tools.
Tool Steel:
Contains tungsten, molybdenum, vanadium, or cobalt.
Properties: High hardness and resistance to heat.
Uses: Cutting tools, molds, dies.
Alloy Steel:
Includes other elements like manganese, silicon, nickel, titanium, or copper.
Properties: Improved strength, toughness, or corrosion resistance.
Uses: Gears, pipelines, aerospace parts.
- Based on Production and Structure:
Hot Rolled Steel:
Process: Rolled at high temperatures.
Properties: Less precise shapes, rough finish, less expensive.
Uses: Construction beams, railroad tracks.
Cold Rolled Steel:
Process: Rolled at room temperature.
Properties: Smooth finish, high dimensional accuracy, more expensive.
Uses: Appliances, furniture.
- Based on Microstructure:
Ferritic Steel:
Body-centered cubic (BCC) structure.
Magnetic, good ductility.
Austenitic Steel:
Face-centered cubic (FCC) structure.
Non-magnetic, highly ductile.
Martensitic Steel:
Formed by rapid cooling (quenching).
Hard, brittle, magnetic.
Duplex Steel:
Mix of austenitic and ferritic.
Properties: High strength and corrosion resistance.
- Specialized Types:
Weathering Steel (Corten):
Resists weather and forms a protective rust layer.
Uses: Bridges, sculptures.
High-Strength Low-Alloy (HSLA) Steel:
Low carbon, small amounts of alloying elements.
Properties: Lightweight, strong, corrosion-resistant.
Uses: Structural beams, shipbuilding.
Electrical Steel:
High silicon content for magnetic properties.
Uses: Transformers, electric motors.
Each type of steel is tailored to its intended purpose, balancing strength, corrosion resistance, and cost.